A small brush with big cleaning power! Keep vent inserts and reservoirs clean in any Dr. Browns bottles with Dr. Browns Cleaning Brushes. Happy Feeding stays happy when you use the Cleaning Brush to clean and clear blockages of dried milk and formula. The multi-purpose, lightweight brush easily maneuvers through all Dr. Browns bottle components especially the Dr. Browns Internal Vent System for a fully clean and functioning bottle interior. Also use to clean sippy and straw cups. Replace lost or worn brushes with this 4-brush pack or just have a few spares on hand! BPA free.